COLUMBUS, Ohio (WCMH) – The yellow school bus plays an iconic role in the back-to-school season, but the bright hue is more than tradition.

With 26 million students riding buses across the U.S. each day, school transportation is considered the country’s largest public transit system. Most school buses are painted a familiar bright yellow. The color helps improve safety and recognition to protect student passengers.

Frank Cyr is known as the “Father of the Yellow School Bus,” although he always believed his standardized color was more of an orange. Cyr was a professor at Columbia University who brought together school bus manufacturers and transportation officials across 48 states for a national safety conference. The conference established national school bus standards, including painting all buses yellow.

Officially known as “National School Bus Glossy Yellow,” the bright yellow color was chosen from 50 swatches hung across a wall. According to Columbia University, where the conference took place, the bright yellow best displayed black text in semi-darkness, like early mornings when a bus might pick up students.

Cyr had decided to host the conference and create the first national school bus standards after researching school transportation. He had found a district in Kansas that only drove students in horse-drawn wheat wagons, while another district was found to have painted its buses red, white and blue to instill patriotism. Cyr was concerned by the lack of consistency and how it could affect bus safety.

Many of the 44 school bus standards agreed upon at Cyr’s conference have changed over the decades, but the color has not. The bright yellow is credited with helping keep students safe; according to the National Highway Traffic Safety Administration, less than 1% of all traffic fatalities involve students on school buses thanks to safety standards like school bus yellow.

Nationally, there are no requirements for school buses to be yellow, although it is recommended. In Ohio, for example, school buses are required to be yellow. A bus can even fail a state inspection if it isn’t the right hue.

Experts say that over millions of years of evolution, humans gained the ability to quickly identify yellow, making them one of the only mammals to develop a third color-processing cone in the eye. According to one study, primates likely developed the ability to see more colors than many other mammals in order to more easily identify ripe, yellow fruit against green foliage.

According to Iowa State University, the human eye is most sensitive to a yellow-green color. At night or in low lighting, eyes process colors differently, but still favor yellow and some green shades. This makes School Bus Glossy Yellow especially visible, even from the periphery, helping ensure drivers are cognizant of student transportation.

As students return to school, transportation safety organizations encourage drivers to remind themselves of bus safety laws and to always look out for the bright yellow bus.